The rotation matrix, why doesn't it work as expected?
There is a rotation matrix
In my program it works correctly, rotate the point at a specified angle, but I can't understand why)) The fact that I tried to turn the point on the paper and multiplies manually (coordinates in a string is multiplied by the matrix), the angle picked up 90 degrees, and the result was as though turned to -90. I looked at the method of multiplying coordinates by a matrix in the program, and tried to perform the same experiment programmatically, I got the same result: rotation in the opposite direction. Maybe someone knows something about this?
1 answers
And what coordinate systems are used on paper and in the program?
The resulting matrix corresponds to a rotation of minus 90 degrees.
How it will look on the screen depends on the mentioned SC.
For a commonly used system with the OY axis pointing down, this will be a counterclockwise rotation.